Twin-screw pump and automatic balancing means therefor



Feb. 17, 1931. w. s. HOLDAWAY 1,792,839

TWIN SCREW PUMP AND AUTOMATIC BALANCINF MEANS THEREFOR Filed A ril 10, 1928 5 Sheets-Sheet l Inventor Attormgy Feb. 17, 1931. w, s HOLDAWAY. 7 1,792,839

TWIN SCREW PUMP AND AUTOMATIC BALANCING MEANS THEREFOR Filed April 10, 1928 5 sh eets sheet 2 S 44* 7Q v E 1 o 73 O o 0 I 45 47 Z7 A Inventor W/W/m LEE/m Attorney Feb. 17, 1931. w. s. HOLDAWAY 1,792,839

TWIN SCREW PUMP AND AUTOMATIC BALANCING MEANS THEREFOR 5 Sheets-Sheet 5 Filed April 10, 1928 Inventor Feb. 17, 1931. w. s. HOLDAWAY 1,792,839

TWIN SCREW PUMP AND AUTOMATIC BALANCING MEANS THEREFOR Filed April 10, 1928 5 Sheets$heet 4 W1? /a awa/a Attornqy Feb. 17, 1931. w s HQLDAWAY 1,792,839

TWIN SCREW PUMP AND AUTOMATIC BALANCING MEANS THEREFOR Filed April 10. 1928 5 Sheets-Sheet 5 Inventor B QM Attarn (9' Patented Feb. 17, 1931 UNITED STATES PATENT; OFFICE WILLIAM S. HOLDAWAY, 01!? SALT LAKE CITY, UTAH, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO D. AND H. MANUFACTURING COMPANY, A CORPORATION OF UTAH TWIN -SCREW PUMP AND AUTOMATIC BALANCING MEANS THEREFOR Application filed April 10,

The present invention relates to twin screw pumps and more particularly to a means for balancing the same, whereby to eliminate end thrust in the pump through the balancing action of counterbalancing means operable with the pump.

An object of the invention resides in providing the combination with a twin screw pump of suitable means connected with each of the pum screws in axial alignment therewith for utilizing the pressure of the fluid in the outlet pipe of the pump and disposed adjacent the intake end of the screws for counteracting and counterbalancing the back pressure exerted on the screws.

Said means also utilizes the weights of the parts' entering into the construction of the pump to increase the effectiveness of the counter-balancing action when the pump is arranged in a vertical position.

The invention further comprehends an apparatus for counterbalancing the pump which consists of a variable pressure in the discharge pipe thereof with the intake end of the pump whereby to offset the variable pressure upon the screws carried by the pump for offsetting the variable pressure to which the screws may be subjected at the discharge end thereof, said counterbalancing apparatus having a predetermined relation with respect to the operating. parts of the pump, whereby to increase the efliciency of the counterbalancing action. The invention further includes the provision of a special means for providing an automatically operated fluid counter-balancing device, in which the parts have a special construction in relation to the operating parts of the pump for obtaining such automatic counter-balancing action.

An additional object of the invention is to provide a housing for the pump having intake and discharge chambers arranged at the opposite ends of the housing and each provided with a plurality of intake and discharge ports, said housing also including a gear chamber within which to enclose the operating gears for the pum screws, ena- 59 bling such gears to run in oi without ap- 1928. Ser1a1 No. 268,858.

preciable loss of the oil therein, into the pump chamber.

The invention further comprehends numerous other objects residing 1n the special details of construction and arrangement of the parts for carrying out the invention as pointed out in the following detailed description, directed to a preferred form of the invention, it being understood, however, that various changes in the size, shape, and arrangement of parts may be made without departing from the spirit or scope of the invention as herein set forth.

In the drawings:

Figure 1 is a side elevational view of the screw pump structure with the counter-balancing mechanism applied thereto, portions being broken away and shown in section.

Figure 2 is a vertical sectional view taken substantially on the line 2-2 of Fi ure 1, the pump structure and counterba ancing mechanism being shown in side elevation.

Figure 3 is an enlarged sectional view through one of the counterbalancing chambers illustrating the manner of rotatably supporting the same.

Figure 4 is a plan view of the pump housing. with the sections thereof adjacent the intake end of the pump broken away to illustrate the interior construction of the intake end of the pump.

Figure 5 is a side elevational view of the pump housing.

Figure 6 is an end elevational view, showing the intake end thereof.

Figure 7 is a side elevational view of one of the combined bearings and end thrust plates for the screws.

fFigure 8 is a front elevational view there- 0 Figure 9 is a group transverse sectional View, through the packing gland and gear and bearing chambers, with the oil division plates interposed therebetween.

Figure 10 is a perspective view ofthe oil division plate.

Figure 11 is a fragmentary sectional view through one of the parts with cover plate shown attached thereto, and

Figure 12 is a plan view of one of the cover plates. I

Heretofore, in the operation of twin screw pumps, itfhas been found that considerable wear, due to end thrustieaused by the back pressure of fluid in the outlet pipe from the pump, occurs to the bearings for the shafts of the screw members, to such an extent that thrust bearings are rapidly worn out and require frequent replacement.

This is especially true where fluid is pumped upwardly any considerable dis-- tance, as the back pressure increases as the height to which the water is pumped also increases.

The resent invention therefore provides means or operation in conjunction with twin screw pumps for equalizing the back pressure from the head of water in the outlet pipe of the pump as well as providing an improved construction in the pump housing enabling the screw operating gear to be enclosed in an oil chamber, arranging intake and discharge chambers at opposite ends of the houslng adapted for convenient removal and replacement, with each of said chambers having a plurality of ports and otherwise to improve the construction of the housing to increase the efliciency in the operation of the pump.

Referring to the detailed construction of the apparatus, the pump is composed of an intake chamber 5, arranged at one end of the pump housing 6 and has its opposite end provided with a discharge chamber 7, said chambers and said ends of the housing being flanged as shown at 8, to provide for the convenient attachment of the chambers to the housing. Each of the chambers, it will be observed, are provided with a plurality of ports for attaching a series of intake and discharge pipes 9 and 10 respectively to the chambers, permitting the rece tion and discharge of fluid at any side 0 the pump.

The pump housing 6 is of an elongated tubular formation, with a pair of simple spiral screws 11, snugly fitted therein and meshed with each other, whereby upon the proper rotation of the screws to force the fluid from the intake toward the discharge end of the housing.

Interposed between the discharge chamber 7 and the adjacent end of the pump housing 6, is arranged a bearing plate 12, having a pair of bosses 13, formed at one face and protruding within the discharge chamber, said plate having openings formed therein in alignment with the center of said bosses, whereby to receive the discharge end of the screw shaft 14, to provide a rotatable mounting for such end of the shaft.

A packing gland 15 is provided for the end of the shaft, arranged in the openings in the plate 12, Within which a suitable lubricant may be carried to facilitate the rotation'of the shaft. A

The plate 12 is provided with a series of perforations 16, through which the fluid from the housing 6 may be forced, through the plate, into the discharge chamber 7. A similar division plate 17 is interposed between the housing and the intake chamber 5, with its edges secured between the flanges of the housing and said chamber, the plate 17 being constructed similarly to the plate 12 and with the bosses 18 thereof protruding within the housing 6 and form ing an abutment for the intake end of the screws, whereby to prevent relatively longitudinalmovement of the screws within the housing.

Packing glands 19 are also provided between the plates 17 and the intake ends of the shaft 14, and the plate 17 is also provided with a series of openings 20, affording communication from the intake chamber 5 into the housing 6.

The shaft 14 extends from the intake vend of the screws 11, through the intake chamber 5, and through openings formed in bearing bosses 22, protruding from one face of a division plate 23, said division plate 23 being socured to the side of the intake chamber 5, opposite from the division plate 17, and forming a closure for such end of the chamber. Extending outwardly from the plate 23 is a packing g and chamber 24, formed of an annular collar having flanges 25, arranged at each end thereof for attaching respectively to the flanges 8 of the intake chamber 5, and with the flanges 26 formed at one end of the gear housing 27. An oil division plate 28 is interposed between the flanges 25 and 26, whereby to form a gear chamber 29, within the housing 27, for enclosing the gears 30, keyed on the shafts 14. The gears 30 are arranged in constant engagement to provide forthe synchronous operation of the shafts 14, and consequently will operate the screws 13 oppositely with respect to each other.

The oil division plate 28 is provided with openings through which the shaft 14 extends and it will be ap arent from an inspection of Figure 4 of t e drawing that the gear chamber 29 may be filled with a quantity of oil to facilitate the rotation of the gears 30.

The end of the bearing housing 27 opposite from the oil division plate 28 is closed with a pair of openings formed in the closed end thereof, for receiving the shafts 14, permitting the same to extend outwardly therefrom and the inner face of the closed end of the housing about said opening is recessed to receive a ball bearing assembly 32 for each of the shafts.

Should the pump be operated under conditions where it is desired to close one or more of either the intake or discharge ports, a cover plate 33 is provided for fitting over rao wardly from the gear housing 27 are .sup-' ported in bearing brackets 35, attached to suitable supporting beams 36, one of said shafts being operatively connected with an electric motor 37 ,said shaft continuing-outwardly from the opposite side of the motor as shown at 38, in continuation of the parallel relation of said shaft.

The electric motor is adapted to be energized from any suitable source of power and controlled in the usual manner for driving the pump screws 11 through the shaft 14.

The outer end of the shaft section 38 carries a counter-balance drum 39, *rigidly mounted on said shaft and rotatable therewith, the drum being rotatably supported at opposite sides between the pair of supporting means 36. A similar counter-balance drum 40 is mounted'at the outer end of the other of said shafts, and likewise supported for rotation therewith between a pair of the supporting beams 36.

Referring more particularly to Figure 3 of the drawings, it will be noted that one end of each counter-balance drum 39 and 40 is.

formed with a recess projection 41, providing a socket to receive the end of its associated shaft, and to which the drums are attached and rigidly secured, as by means of set screws 42.

The drums are of hollow construction with the upper ends provided with journals 43,- projecting upwardly in axial alignment with the shaft on which the drums are mounted, said journals being rotatably supported in the bearing brackets 44 of the supporting beams 36.

The journal 43 is provided with a cylindrical bore 45, through which a extended, having communication with the interior of the drum. The pipe carries a collar 47 adapted to snugly fit within the bore 45, and against which collar is seated a series of packing rings 48, arranged for compressi'ng against the collar 47, by a packing nut 49, 52nd packing nut being screw threaded With- I in the outer end of the journal.

The pipes 46 communicating with the respective drums are provided with cut-off valves 50, having a connection through the pipe 51 with the discharge pipe 10. The fluid pressure from the discharge pipe is admitted to the drums 39 and 40 through the pipe 51 and the respective valves to exert a counterbalancing pressure on the shafts 14.

The size of the drums is governed entirely by the character of the pumps to which they are applied for the purpose of counter-balancing the back pressure at the discharge end of the screws 11.

pipe 46 is a The requiredcounter-balancing action of fluid in the drum will be equal to the back pressure in the pipe 51 on the screws, less the weight of the screw and the other associated parts supported by the shaft, when the pump is disposed vertically.

This is because of the fact that the weight of these parts efiects a counterbalancing of the screws to the extent of their weight and it is desired to add in combination with this,

weight back pressure to counter-balance the back pressure of the discharge ends of the screws. The relative weight of each of the shafts is therefore accurately determined and the counter-balanced drums 39 and 40 are calculated to have an interior area so that the pressure in the pipe 51 applied therein through the pipes 46 will equalize the back pressure'caused by the fluid in the pipe 51, on the discharge ends of the screws 11.

When mounted for operation in a horizontal position, the pump may be supported upon a pair of feet 52, attached to the under side of the intake and discharge chamber.

The pump may also be used as-a lifting pump for shallow wells by removing the discharge 7 and suspending the pump housing in the well and reversing the operation of the screws 11, so as to draw the fluid into the housing 6, through the openings in the plate 12 and outwardly through the ports of the intake chamber. It will be apparent that the pump housing assembly may be immersed in the water or other liquid being pumped, without danger of the liquid or sediment contained therein coming into contact with the gears, the gear housing 27 serving to protect said gears from interference during the operation thereof.

It is also apparent that the various parts of the pump housing assembly may be easily and quickly removed and replaced, when'desired, to meet particular conditions encountered during the operation thereof.

It is obvious that the invention is susceptible of various changes and modifications, without departing from the spirit or scope of the invention or sacrificing any of its advantages, and I accordingly claim all suchforms of the device to which I am en- Y the shafts and cooperating with the'motor to exert their combined weights axially on the shafts for opposing the back pressure at the discharge ends of the screws and feed pipes connecting the discharge ports of the chamber with said containers for feeding fluid under pressure thereto axially of the shaft and providing counter-balancing means for 5 the discharge ends of the screws, variable in accordance with the pressure created by the screw.

2. A counterbalancing structure for pumps comprising a pair of cooperating spiral impellers having their axes disposed vertically and their discharge ends positioned downwardly, drive shafts for the impellers extending therefrom and fluid containers supported upon the shaft having communication with the discharge end of the impellers and providing gravity means for applying pressure axially of the shaft for opposing hack pressure of the impellers.

3. A counterbalancing structure for pumps comprising a pair of cooperating spiral screw impellers having their axes disposed vertically. and their discharge ends positioned downwardly, drive shafts for the impellers extending upwardly therefrom, fluid containers secured to the shaft for rotation therewith and fluid feed pipes comn'iunicating with the discharge ends of the impellers and having one end slidably inserted in the top of the respective containers axially of the shaft whereby to utilize the gravitating force of the container and the fluidfed into the containers to oppose back pressure of the impellers.

In testimony whereof I affix my signature.

WILLIAM S. HOLDAWVAY. 

